diff --git a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/v1/Publisher.java b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/v1/Publisher.java
index 1ed5e2254..f59333dd3 100644
--- a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/v1/Publisher.java
+++ b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/v1/Publisher.java
@@ -655,8 +655,8 @@ public static final class Builder {
 
     // Meaningful defaults.
     static final long DEFAULT_ELEMENT_COUNT_THRESHOLD = 100L;
-    static final long DEFAULT_REQUEST_BYTES_THRESHOLD = 1000L; // 1 kB
-    static final Duration DEFAULT_DELAY_THRESHOLD = Duration.ofMillis(1);
+    static final long DEFAULT_REQUEST_BYTES_THRESHOLD = 1L * 1024L * 1024L; // 1 MB
+    static final Duration DEFAULT_DELAY_THRESHOLD = Duration.ofMillis(10);
     private static final Duration DEFAULT_INITIAL_RPC_TIMEOUT = Duration.ofSeconds(5);
     private static final Duration DEFAULT_MAX_RPC_TIMEOUT = Duration.ofSeconds(60);
     private static final Duration DEFAULT_TOTAL_TIMEOUT = Duration.ofSeconds(600);